Exercise details change mysteriously

I've been cycling the same route three times in three days now. When I stop the exercise I can see that all details are fine. After an hour or two I take a look at the exercise details and many of the details have changed; actually dropped to a fraction of the original. Distance has gone from 11.94 km to 0.27 km. Heart rate details are almost gone and calories are way off. It happens every time after a couple of hours. I have OnePlus 6T and Mobvoi Ticwatch S2.